Re: `Alias this` to a mixed in property
On Wednesday, 24 January 2018 at 14:21:42 UTC, ag0aep6g wrote:
The spec says that you cannot make an overload set just by
mixing in multiple functions/methods with the same name.
Instead, you have to do it like this:
mixin getter g;
mixin setter!int s;
alias p = g.p;
alias p = s.p;
https://dlang.org/spec/template-mixin.html#mixin_scope
Thanks a lot! I didn't know you could do overloads by way of
multiple aliases with the same name.
I meant to use this for mixing in multiple instantiations
generated from a static foreach over an AliasSeq of types, but
generating unique identifiers poses an extra challenge.
I may go for string mixin's instead, which I just discovered do
work:
```
import std.stdio;
enum getter = `
@property int p()
{
writeln(__LINE__, " mixin getter");
return 3;
}
`;
string setter(string T) pure
{ return `
@property int p(` ~ T ~ ` arg)
{
writeln(__LINE__, " mixin setter ` ~ T ~ `" , arg);
return 4;
}
`;
}
struct S
{
mixin(getter);
mixin(setter("int"));
alias p this;
}
void main(string[] args)
{
S s;
s = 7;
int i = s;
}
```
Re: `Alias this` to a mixed in property
On 01/24/2018 02:24 PM, Bastiaan Veelo wrote: `Alias this` to mixed in properties does not seem to work, see below. If you think it should, I'll file an issue. Otherwise: can this be made to work somehow? Not supposed to work as it is. The spec says that you cannot make an overload set just by mixing in multiple functions/methods with the same name. Instead, you have to do it like this: mixin getter g; mixin setter!int s; alias p = g.p; alias p = s.p; https://dlang.org/spec/template-mixin.html#mixin_scope
`Alias this` to a mixed in property
Hi,
`Alias this` to mixed in properties does not seem to work, see
below. If you think it should, I'll file an issue. Otherwise: can
this be made to work somehow?
Interestingly, if you uncomment either the mixin getter or setter
(row 36 or 37) and its corresponding use in `main`, then the
remaining property works. Does the compiler detect identical
names and then does some additional mangling which messes with my
`alias this` maybe?
```
import std.stdio;
// version = manual; // Manually written property works,
obviously.
mixin template getter()
{
@property int p()
{
writeln(__LINE__, " mixin getter");
return 3;
}
}
mixin template setter(T)
{
@property int p(T arg)
{
writeln(__LINE__, " mixin setter ", typeid(T), ' ', arg);
return 4;
}
}
struct S
{
version (manual) {
@property int p()
{
writeln(__LINE__, " manual getter");
return 3;
}
@property int p(int arg)
{
writeln(__LINE__, " manual setter int ", arg);
return 4;
}
}
else {
mixin getter;// row 36
mixin setter!int;// row 37
}
alias p this;
}
void main(string[] args)
{
S s;
s = 7;
int i = s;
}
```
Error: cannot implicitly convert expression s of type S to int.
